Mitsubishi Galant 9G. Manual - part 249

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-72

STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect scan tool MB991958 to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : The procedure is complete.
NO : Return to Step 1.

DTC B1041, B1042: Air Mixing Damper Control Motor and Potentiometer (Potentiometer system)

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AIR MIXING
DAMPER CONTROL
MOTOR AND
POTENTIOMETER

JOINT
CONNECTOR (2)

A/C-ECU

Air Mixing Damper Control Motor Potentiometer Circuit

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-73

DTC SET CONDITION

• DTC B1041 or B1042 is set if there is an open or

short circuit in the potentiometer input circuit, or if
there is an open circuit in the power circuit or
earth circuit.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

• The A/C-ECU, the air mixing damper control

motor and potentiometer, or connector(s) or wir-
ing between the two may be defective.

Past trouble

• If DTC B1041 or B1042 is stored as a past trou-

ble, carry out diagnosis with particular emphasis
on wiring and connector(s) between the A/C-ECU
and the air mixing damper control motor and
potentiometer. If the connectors and wiring are
normal, and obviously the ECU is the cause of
the trouble, replace the ECU. If in doubt, do not
replace the ECU.

TROUBLESHOOTING HINT

• Malfunction of connector.

• Malfunction of the harness.

• Malfunction of the air mixing damper control

motor and potentiometer.

• Malfunction of the A/C-ECU.

AC305231AZ

CONNECTOR: C-03

AC305233

C-16 (B)

C-15 (B)

C-105

CONNECTORS: C-15, C-16, C-105

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-74

DIAGNOSIS

Required Special Tool:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN

communication system)

STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.
Use scan tool MB991958 to diagnose the CAN bus lines.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to "ON" position.
(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?

YES : Go to Step 2.
NO : Repair the CAN bus lines. (Refer to GROUP 54C,

Diagnosis-Can Bus Diagnostic Chart

P.54C-607

Then go to Step 7.

STEP 2. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is set.
Q: Is the check result satisfactory?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

− How to

Cope with Intermittent Malfunctions

P.00-14

NO : Go to Step 3.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-75

STEP 3. Using scan tool MB991958, check data list item 10:
air mix potentiometer.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine.
(3) Set scan tool MB991958 to the data reading mode for item

10: air mix potentiometer.

• Check that the set position of the heater control matches

the displayed position on the scan tool.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor within the specified range?

YES : Replace the A/C-ECU. Then go to Step 7.
NO : Go to Step 4.

STEP 4. Check A/C-ECU connectors C-15, C-16 and air
mixing damper control motor and potentiometer connector
C-105 for loose, corroded or damaged terminals, or
terminals pushed back in the connector.
Q: Are A/C-ECU connectors C-15, C-16 and air mixing

damper control motor and potentiometer connector
C-105 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to GROUP

00E, Harness Connector Inspection

P.00E-2

. Then go

to Step 7.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305234

C-16 (B)

HARNESS SIDE

C-16

C-15

C-15 (B)

HARNESS SIDE

CONNECTORS: C-15, C-16, C-105

C-105

HARNESS SIDE

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